Rapid Cu–Cu bonding by pressure-sintering of anti-oxidized Cu nanoparticle pastes under ambient atmosphere

The application of wide bandgap semiconductor devices requires high-performance interconnect materials which have high thermal conductivity and high-temperature resistance. Among which, Cu nanoparticle paste sintering technology is regarded as an advanced alternative. However, Cu nanoparticles are easy to be oxidized, which needs an inert or vacuum atmosphere during the sintering process that restrict the practical application of Cu sintering technology. In this paper, a new type of Cu nanoparticle paste with antioxidation property was prepared by mixed commercial Cu nanoparticles (average diameter: 100 nm) treated by formic acid and reducing solvents containing 1-dodecanethiol. Based on the Cu nanoparticle paste, the pressure-assisted bonding at different bonding temperatures and times was carried out without using any protective atmosphere. A remarkable high shear strength of 55.06 MPa for Cu–Cu joints formed by sintering of Cu nanoparticle paste was achieved when sintered at 250 °C. The results of bonding experiment suggest that the proposed Cu nanoparticle paste has excellent antioxidation property and shows great application potential in high power electronic packaging.